[llvm build] Host compiler must support std::atomic

[tesuji]

I cannot build rustc locally with commit f7af19c.

The build log is:

% ./x.py test src/test/ui --pass check
Updating only changed submodules
Submodules updated in 0.06 seconds
    Finished dev [unoptimized] target(s) in 0.21s
Building stage0 std artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
    Finished release [optimized] target(s) in 0.29s
Copying stage0 std from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
Building stage0 test artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
    Finished release [optimized] target(s) in 0.22s
Copying stage0 test from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
Building stage0 compiler artifacts (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu)
    Finished release [optimized] target(s) in 0.27s
Copying stage0 rustc from stage0 (x86_64-unknown-linux-gnu -> x86_64-unknown-linux-gnu / x86_64-unknown-linux-gnu)
Building LLVM for x86_64-unknown-linux-gnu
running: "cmake" "/home/lzutao/forked/rust/compiler-rust/src/llvm-project/llvm" "-G" "Ninja" "-DLLVM_ENABLE_ASSERTIONS=OFF" "-DLLVM_TARGETS_TO_BUILD=AArch64;ARM;X86" "-DLLVM_EXPERIMENTAL_TARGETS_TO_BUILD=" "-DLLVM_INCLUDE_EXAMPLES=OFF" "-DLLVM_INCLUDE_TESTS=OFF" "-DLLVM_I
NCLUDE_DOCS=OFF" "-DLLVM_INCLUDE_BENCHMARKS=OFF" "-DLLVM_ENABLE_ZLIB=OFF" "-DWITH_POLLY=OFF" "-DLLVM_ENABLE_TERMINFO=OFF" "-DLLVM_ENABLE_LIBEDIT=OFF" "-DLLVM_ENABLE_Z3_SOLVER=OFF" "-DLLVM_PARALLEL_COMPILE_JOBS=32" "-DLLVM_TARGET_ARCH=x86_64" "-DLLVM_DEFAULT_TARGET_TRIPLE=
x86_64-unknown-linux-gnu" "-DLLVM_OCAML_INSTALL_PATH=usr/lib/ocaml" "-DLLVM_LINK_LLVM_DYLIB=ON" "-DLLVM_ENABLE_LIBXML2=OFF" "-DLLVM_VERSION_SUFFIX=-rust-1.39.0-dev-48818e9f5" "-DPYTHON_EXECUTABLE=/home/lzutao/.local/bin/python2.7" "-DCMAKE_INSTALL_MESSAGE=LAZY" "-DCMAKE_C
_COMPILER_LAUNCHER=ccache" "-DCMAKE_CXX_COMPILER_LAUNCHER=ccache" "-DCMAKE_C_COMPILER=cc" "-DCMAKE_CXX_COMPILER=c++" "-DCMAKE_C_FLAGS=-ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_CXX_FLAGS=-ffunction-sections -fdata-sections -fPIC -m64" "-DCMAKE_INSTALL_PREFIX
=/home/lzutao/forked/rust/compiler-rust/build/x86_64-unknown-linux-gnu/llvm" "-DCMAKE_BUILD_TYPE=Release"
-- Could NOT find Z3: Found unsuitable version "0.0.0", but required is at least "4.7.1" (found Z3_LIBRARIES-NOTFOUND)
CMake Error at cmake/modules/CheckAtomic.cmake:50 (message):
  Host compiler must support std::atomic!
Call Stack (most recent call first):
  cmake/config-ix.cmake:349 (include)
  CMakeLists.txt:618 (include)


-- Configuring incomplete, errors occurred!
See also "/home/lzutao/forked/rust/compiler-rust/build/x86_64-unknown-linux-gnu/llvm/build/CMakeFiles/CMakeOutput.log".
See also "/home/lzutao/forked/rust/compiler-rust/build/x86_64-unknown-linux-gnu/llvm/build/CMakeFiles/CMakeError.log".
thread 'main' panicked at '
command did not execute successfully, got: exit code: 1

build script failed, must exit now', /home/lzutao/.cargo/registry/src/github.com-1ecc6299db9ec823/cmake-0.1.38/src/lib.rs:813:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace.
        finished in 0.100
failed to run: /home/lzutao/forked/rust/compiler-rust/build/bootstrap/debug/bootstrap test src/test/ui --pass check
Build completed unsuccessfully in 0:00:02

---

Host machine

% uname -a
Linux gcc122.bak.milne.osuosl.org 4.9.0-9-amd64 #1 SMP Debian 4.9.168-1+deb9u2 (2019-05-13) x86_64 GNU/Linux

Custom config.toml

--- config.toml.example 2019-08-09 12:13:49.714819942 +0000
+++ config.toml 2019-08-09 17:26:12.650918099 +0000
@@ -30,7 +30,7 @@
 #assertions = false
 
 # Indicates whether ccache is used when building LLVM
-#ccache = false
+ccache = true
 # or alternatively ...
 #ccache = "/path/to/ccache"
 
@@ -46,7 +46,7 @@
 # Tell the LLVM build system to use Ninja instead of the platform default for
 # the generated build system. This can sometimes be faster than make, for
 # example.
-#ninja = false
+ninja = true
 
 # LLVM targets to build support for.
 # Note: this is NOT related to Rust compilation targets. However, as Rust is
@@ -57,12 +57,13 @@
 # support. You'll need to write a target specification at least, and most
 # likely, teach rustc about the C ABI of the target. Get in touch with the
 # Rust team and file an issue if you need assistance in porting!
-#targets = "AArch64;ARM;Hexagon;MSP430;Mips;NVPTX;PowerPC;RISCV;Sparc;SystemZ;WebAssembly;X86"
+targets = "AArch64;ARM;X86"
 
 # LLVM experimental targets to build support for. These targets are specified in
 # the same format as above, but since these targets are experimental, they are
 # not built by default and the experimental Rust compilation targets that depend
-# on them will not work unless the user opts in to building them.
+# on them will not work unless the user opts in to building them. By default the
+# `WebAssembly` and `RISCV` targets are enabled when compiling LLVM from scratch.
 #experimental-targets = ""
 
 # Cap the number of parallel linker invocations when compiling LLVM.

[andjo403]

what gcc version are you using?
when did it work last time? a week ago llvm-project submodule was updated last time

[tesuji]

what gcc version are you using?

% gcc -v
Using built-in specs.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/home/lzutao/.local/libexec/gcc/x86_64-pc-linux-gnu/9.1.0/lto-wrapper
Target: x86_64-pc-linux-gnu
Configured with: ../gcc-9.1.0/configure --prefix=/home/lzutao/.local --enable-languages=c,c++
Thread model: posix
gcc version 9.1.0 (GCC) 
% cc -v
clang version 10.0.0 (https://github.com/llvm/llvm-project.git 2bf522aea62e4fb653cacb68072167d25149099e)
Target: x86_64-unknown-linux-gnu
Thread model: posix
InstalledDir: /home/lzutao/.local/bin
Found candidate GCC installation: /home/lzutao/.local/bin/../lib/gcc/x86_64-pc-linux-gnu/9.1.0
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6
Found candidate GCC installation: /usr/lib/gcc/x86_64-linux-gnu/6.3.0
Selected GCC installation: /home/lzutao/.local/bin/../lib/gcc/x86_64-pc-linux-gnu/9.1.0
Candidate multilib: .;@m64
Candidate multilib: 32;@m32
Selected multilib: .;@m64

when did it work last time?

Probably a few days ago. Then I hit git clean -xfd at root dir of the repo and cause
llvm to be rebuilt.

[andjo403]

strange the atomic test code works on godbolt as expected.
can it be some problem with the ccache?

[tesuji]

Thanks. This shall be problem with my llvm build

% clang -std=c++11 test.cpp
ld: error: undefined symbol: __cxa_begin_catch
>>> referenced by test.cpp
>>>               /tmp/test-64b1e6.o:(__clang_call_terminate)

ld: error: undefined symbol: std::terminate()
>>> referenced by test.cpp
>>>               /tmp/test-64b1e6.o:(__clang_call_terminate)

ld: error: undefined symbol: __gxx_personality_v0
>>> referenced by test.cpp
>>>               /tmp/test-64b1e6.o:(.eh_frame+0x6B)
clang-9: error: linker command failed with exit code 1 (use -v to see invocation)

I will check it later and report here.

[tesuji]

I rebuilt and install clang from scratch. rust llvm has been build fine since then.
Closing as not a bug.

Thanks @andjo403 for the help you give.